1. Field of the Invention
The present invention relates to a digital audio signal output device, and more particularly to a post processor for processing digital audio data on the fly (in real time), a digital audio data output device including the post-processor, and a method of outputting digital audio data.
2. Description of the Related Art
A conventional digital audio data output device outputs audio data in various formats. The conventional digital audio data output device typically processes the digital audio data using a high performance digital signal processor (DSP) and outputs processed digital audio data.
FIG. 1 is a block diagram illustrating a conventional digital audio data output device.
The digital audio data output device 100 includes an input unit 101, a first memory 102, a DSP core 103, a second memory 104 and transmitters 105 and 106. The input unit 101 may receive the digital audio data in stereo mode as two channel data. The first memory 102 may be a first FIFO memory and stores (buffers) the digital audio data temporarily. The DSP core 103 processes the digital audio data stored in the first memory 102. The second memory 103 may be a second FIFO memory and temporarily stores (buffers) the digital audio data processed by the DSP core 103. The transmitters 105 and 106 transmit the processed (stereo) digital audio data according to a predetermined transmission mode.
The DSP core 103 reads (stereo) digital audio data stored in the first memory 102 and processes the digital audio data in mono mode (such as single left channel mode, single right channel mode), or in mix (stereo) mode. The DSP core 103 adjusts volume level per channel of digital audio data. The DSP core 103 may perform mute operations according to mute setting.
The DSP core 103 included in the conventional digital audio data output device 100 performs not only processing of digital audio data but also operations requested by other circuits (not shown).
When many devices request the DSP core 103 for digital audio data of different channel mode and different volume, the amount of processing operations (computations per second) for processing the digital audio data increases. For example, when the first transmitter 105 is required to output digital audio data in stereo mode, and the second transmitter 106 is required to output digital audio data in mix mode, the DSP core 103 needs to perform both operations simultaneously for generating the digital audio data to be outputted from the first transmitter 105 and the digital audio data to be outputted the second transmitter 106.
When operations requested by other circuits increase, or digital audio data needs to be processed for many devices, the DSP core 103 may not be able to process all the buffered (in first memory 102) digital audio data on the fly (in real time, without significant delay).
The transmitters 105 and 106 use digital audio data stored in the second memory 104, because the transmitters 105 and 106 may not immediately transmit the digital audio data processed and output by the DSP core 103.
As described above, much time (delay) and a large amount of buffer memory may be required to process and output the digital audio data in the conventional digital audio data output device.